Geodiversity Action Plan Cornwall and the Isles of Scilly 2005

Transcription

1 Geodiversity Action Plan Cornwall and the Isles of Scilly 2005 Written by: Paul Wheeler Edited by: Paul Wheeler, Sarah Board, Peter Ealey and Sue Hocking Bibliographical reference: WHEELER, P.D Geodiversity Action Plan, Cornwall and the Isles of Scilly. 1st Edition. Cornwall Wildlife Trust, Truro, UK. Copyright Environmental Records Centre for Cornwall and the Isles of Scilly and English Nature. First published by the Environmental Records Centre for Cornwall and the Isles of Scilly. ISBN

2 Key Definitions Geodiversity - geological diversity is the variety of rocks, minerals, fossils (i.e. the geology), together with the variety of soils, natural processes and landforms (the geomorphology) found within a particular region. These all combine with a region s biodiversity and human activities (farming, townbuilding, mining etc.) to provide the landscapes or scenery. Geology - the study of the Earth as a whole; its origin, structure, composition and history (including the evolution of life) plus the natural processes which affect it. The term earth sciences is often used as an all encompassing term for geology, physical geography, climatology and oceanography. Geomorphology - the study, description and identification of processes which affect the Earth s surface (geomorphic processes) and the features, such as rivers, beaches, granite tors etc. that result (landforms). Geological resources - encompasses rock types, mineral deposits and building materials for which humans have a use; soils for habitat and agriculture/forestry; as well as the human skills involved in all aspects of geology, geomorphology and geoconservation. Geoconservation - the conservation of geodiversity for its intrinsic, ecological and heritage values. Geoconservation seeks to maintain and conserve natural geological, geomorphological, soil and landscape features for their value as natural phenomena, not simply because of their direct usefulness to humans. Geodiversity Action Plan (GAP) - a document with objectives, targets, action plans and indicators to measure success; which highlights priorities for, and focuses resources on, the conservation and promotion of geodiversity in a region. GAPs often include an audit of resources i.e. a study of what geological features, geomorphology, resources etc. there are in a particular region. Biodiversity - biological diversity, literally meaning the variety of life found within a particular region. A more formal definition is the variability among living organisms and the ecological complexes (ecosystems) of which they are part. Biodiversity therefore encompasses all organisms, plant and animal species as well as the habitats and areas in which they are found. Exposure sites - these are sites whose scientific or educational value lies in providing current exposures of a geological feature(s) which is laterally and vertically extensive or widespread below the surface; i.e. the actual features of interest could be exposed elsewhere if required, to form equally suitable exposures (e.g. by continued quarrying or on-going coastal erosion). Such exposure sites are numerically the most common category of sites and include most cliffs, quarries, road-cuttings and natural outcrops. Their conservation depends on preserving suitable areas of exposure, and it is possible for new exposure sites of a feature to be created. Integrity sites - these are sites whose scientific or educational value lies in the fact that they contain scarce deposits, features or landforms that cannot be recreated if damaged or destroyed. The usual situation is that the deposit or landform is of relatively recent age and of limited lateral extent, although many older geological features also fall into this category because of their rarity. Examples include periglacial deposits and unique mineral, fossil, stratigraphic, or structural features. Integrity sites are, by definition, finite and irreplaceable. The approach to their conservation is to maintain the integrity of the feature and often implies active conservation and restriction of man-made changes. Sustainable development - development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Implies aspects of growth and increase (i.e. development) but in an environmentally responsible manner. A Glossary has been included at the end of this Action Plan to explain some of the more technical (geological) terms used.

3 CONTENTS LIST OF FIGURES... III LIST OF TABLES... III ACKNOWLEDGEMENTS... IV EXECUTIVE SUMMARY... 1 CHAPTER 1 INTRODUCTION OVERVIEW GEODIVERSITY ACTION PLAN OBJECTIVES SOURCES OF INFORMATION AND CONSULTATION Key Sources of Information Consultation Process SUMMARY CHAPTER 2 GEODIVERSITY AUDIT SCOPE OF AUDIT Approach Geological SSSIs and GCR sites County Geology Sites (RIGS) Other Nature Conservation Sites GEOLOGICAL HISTORY SEDIMENTARY BASINS Pre-Devonian Basement Looe Basin Gramscatho Basin Trevone-South Devon Basin Tavy Basin Culm Basin Additional Findings VARISCAN STRUCTURES, METAMORPHISM AND THE LIZARD COMPLEX Variscan Structures Regional Metamorphism Lizard Complex GRANITES AND MINERALISATION Granites Associated Rocks Mineralisation and Alteration Mineral Specimens MORE RECENT SEDIMENTS Offshore Geology Tertiary Quaternary Sediments SOILS, LANDSCAPE AND GEOMORPHOLOGY Soils Landscape and Geomorphology ECONOMIC GEOLOGY Aggregates and Building Stone China Clay Metals and Other Resources AVAILABLE SKILLS AND RESOURCES Skills Data Collection and Storage Site Management SUMMARY Geodiversity Action Plan, Cornwall and Isles of Scilly i

4 CHAPTER 3 ISSUES AFFECTING GEODIVERSITY INTRODUCTION MINERAL EXTRACTION AND RESTORATION Review Key Issues AGRICULTURE AND FORESTRY Review Key Issues WASTE DISPOSAL AND DERELICT LAND Review Key Issues BUILT DEVELOPMENT Review Temporary Exposures Key Issues TOURISM, AMENITY USE AND ACCESS Review Access Museums and Collections Key Issues COASTAL EROSION AND CLIMATE CHANGE Review Key Issues MINERAL AND SPECIMEN COLLECTING Key Issues SUMMARY CHAPTER 4 PLANNING AND CONSERVATION POLICIES INTRODUCTION LAND USE PLANNING CORNWALL STRUCTURE PLAN GEODIVERSITY AND CONSERVATION DESIGNATIONS ISLES OF SCILLY MINERALS PLANNING WORLD HERITAGE SITE BID WORKING PRACTICES SUMMARY CHAPTER 5 PUBLIC AWARENESS AND APPRECIATION INTRODUCTION UNDERSTANDING OF CONSERVATION AND SCIENCE CURRENT STATUS TARGET SECTORS FURTHER OPPORTUNITIES SUMMARY CHAPTER 6 RECOMMENDATIONS INTRODUCTION RECOMMENDATIONS ARISING FROM THE KEY ISSUES Recommendations, Action Plans and Targets CHAPTER 7 ACTION PLANS Geodiversity Action Plan, Cornwall and Isles of Scilly ii

5 7.1 INTRODUCTION Priority targets ACTION PLAN 1: SET-UP INFRASTRUCTURE TO DELIVER THE GAP ACTION PLAN 2: COMPLETE RESOURCES AND SKILLS AUDIT ACTION PLAN 3: IMPROVE DATA COVERAGE (PLANS 3A, 3B AND 3C) ACTION PLAN 4: IMPROVE POLICY AND WORKING PRACTICES ACTION PLAN 5: RAISE PUBLIC AWARENESS ACTION PLAN 6: PROMOTE SUSTAINABLE GEOTOURISM AND AMENITY USE ACTION PLAN 7: INCREASE CORPORATE AWARENESS ACTION PLAN 8: IMPROVE LINKS WITH BIODIVERSITY AND HISTORIC ENVIRONMENT SECTORS CHAPTER 8 MONITORING AND EVALUATION INTRODUCTION GEODIVERSITY ACTION PLAN MONITORING GAP Indicators Monitoring of Sites MONITORING AND EVALUATION PLAN APPENDIX 1: KEY SOURCES OF INFORMATION APPENDIX 2: LIST OF CONSULTEES APPENDIX 3: GEOLOGICAL SSSI DESIGNATIONS APPENDIX 4: DESIGNATED COUNTY GEOLOGY SITES REFERENCES GLOSSARY List of Figures Figure 1A: Location of geological or geomorphological related designated sites in Cornwall and the Isles of Scilly. Figure 1B: Location of other (non-geological) nature or landscape conservation sites in Cornwall and the Isles of Scilly. Figure 2: Simplified geological map of Cornwall showing major sedimentary basins and granite plutons. List of Tables Table 1: Conservation sites list for selected aspects of Cornwall and the Isles of Scilly s geodiversity (as at 31/12/04). Table 2: Type and coverage of designated sites and nature reserves in Cornwall and the Isles of Scilly. Table 3: Summary of Geodiversity Issues in Cornwall and the Isles of Scilly Geodiversity Action Plan, Cornwall and Isles of Scilly iii

6 Acknowledgements The author wishes to thank Sarah Board and Sue Hocking (ERCCIS, Cornwall Wildlife Trust) and Peter Ealey (Chairman, Cornwall RIGS Group) for their considerable efforts in reviewing and editing successive versions of this draft. Thanks are due to members of the Cornwall RIGS Group Committee for their input at several draft stages and to Simon Camm, Emma Clarke and Sarah McCartney for assistance with the graphics and report presentation. Also greatly appreciated were the comments and corrections received from individuals and organisations during the external consultation period. Any factual errors that remain are the authors. Cornwall WildlifeTrust acknowledges the support of English Nature in the production of this Geodiversity Action Plan, through DEFRA s Aggregates Levy Sustainability Fund. Geodiversity Action Plan, Cornwall and Isles of Scilly iv

7 Geodiversity Action Plan, Cornwall and the Isles of Scilly 1 st Edition, 2005 Executive Summary Introduction Some 400 million years ago, the geology in Cornwall and the Isles of Scilly evolved in a completely different manner to the rest of Britain; giving rise to a distinctive suite of rocks (slates, greenstones, serpentine, gabbro and granites) and generating one of the world s classic mineralised orefields. As a result Cornwall and the Isles of Scilly have a great diversity of rocks, soils, landscapes and mineral deposits, reflecting their rich and varied geological heritage. Geodiversity is the name given to the variety of rocks, minerals and fossils (geology), together with the variety of soils, natural processes and landforms (geomorphology). Geodiversity is important to Cornwall and Isles of Scilly because: Geology and landscape are the basis for much of Cornwall and Isles of Scilly s beautiful scenery and provide the resources for a variety of recreational and leisure activities. Within our towns, villages and workplaces, geodiversity provides the building materials, architectural heritage and physical landscape. Our natural heritage and historic environment are seen by many as major benefits of living and working in Cornwall and Isles of Scilly. Soils, rocks and landscapes are an integral part of the natural history of Cornwall and Isles of Scilly. They provide the raw materials for active processes to shape our moors, rivers and coasts; creating varied habitats and ecosystems and having an underpinning control on the diversity of wildlife. Cornwall and Isles of Scilly s geodiversity is important in the historical development of geology and mining and retains its importance today as a scientific, cultural and economic resource of national and international significance. Many locations in Cornwall and Isles of Scilly are recognised as Sites of Special Scientific Interest (SSSI) or County Geology Sites (RIGS) for their geological significance, and their conservation and continued protection is a responsibility we have to future generations. There is a pressing need to conserve and manage geodiversity, in the same way that biodiversity conservation has already been incorporated into all levels of national and local policy making, industrial and economic development and education/lifelong learning. Framework The aim of this Geodiversity Action Plan (GAP) is to provide both a strategic framework for geodiversity in Cornwall and Isles of Scilly and to identify projects and actions which take the development or conservation of geodiversity forward in a Geodiversity Action Plan, Cornwall and Isles of Scilly

8 sustainable manner. The GAP includes an audit of Cornwall and Isles of Scilly s geodiversity, in order to identify and summarise the current status of our geological assets, and develops targets and action plans to help manage future work. There are considerable resources and geological skills within Cornwall and the Isles of Scilly, but they are dispersed in various organisations and need harnessing and coordinating to effectively implement the Geodiversity Action Plan. The most critical action required from this GAP is to establish a network of partners willing to support its aims and objectives; with a shared and agreed view on how the action plans will be delivered and funded. The positive feedback received at the consultation stage suggests that establishing a steering group of key partners will be achievable. Considerable progress on geological conservation in Cornwall and the Isles of Scilly has been made through the dedicated efforts of part-time, largely voluntary groups (in particular the Cornwall RIGS Group) and individuals; and work towards the aims and objectives of this GAP will continue. If geodiversity and its conservation is to reach parity with that now enjoyed by biodiversity and the historic environment, however, it needs proper funding and a more full time approach. This Geodiversity Action Plan therefore assumes that there is an individual (nominally called the Geodiversity Officer) tasked with its implementation. The absence of such an appointee should not, however, invalidate attempts to pursue the targets and actions outline in this Geodiversity Action Plan. Whether future funding to support implementation of the Geodiversity Action Plan comes from a single, or a variety of sources, it is important that no one organisation should be seen to have ownership of the GAP and that responsibility for promoting, enhancing and conserving geodiversity in Cornwall and Isles of Scilly is shared by all partners. Range & status of geodiversity sites For almost all aspects of Cornwall and Isles of Scilly s geodiversity there are representative exposure and integrity sites available, although for reasons of safety (for example in relation to underground exposures or mineral resources) or land management (e.g. soils in cultivation) not all may be visible or accessible. Away from the coastal regions and granite tors, the main sites for hard-rock features are provided by current mineral extraction activities and by abandoned mines and quarries. Soils, geomorphological features and the various landscape characters are largely under the stewardship of major landowners and/or agricultural interests. These natural resources achieve regional, national or even international importance in their own right; providing considerable geodiversity value and requiring good management and sustainable development. Existing planning policies for minerals, environmental protection, character areas and use of resources are all aimed at maintaining this range of natural resources and promoting their sustainable development. Although sufficient sites exist in Cornwall and Isles of Scilly to provide representative coverage of almost all aspects of geodiversity, this does not correlate directly with the range and number of sites protected under legislation, various conservation designations or planning policy. Geodiversity Action Plan, Cornwall and Isles of Scilly

9 Geodiversity Audit: key issues 1. Good designated site coverage for: i. Trevone-South Devon Basin in west Cornwall ii. Tavy Basin along north coast iii. Culm Basin iv. regional metamorphic effects on sediments and volcanics v. Lizard Complex vi. Cornubian granite batholith and associated rocks (exceptions shown in 2.iii.) vii. key mineral species locations 2. Under-represented or poor designated site coverage for: i. Trevone-South Devon Basin in east Cornwall ii. Tavy Basin away from the north coast iii. Carnmenellis and Isles of Scilly granite plutons; lamprophyres iv. styles of mineralization and alteration v. Tertiary sediments 3. Insufficient work carried out to date to confirm coverage for: i. Gramscatho Basin ii. Variscan and sedimentary basin structural geology iii. integrity sites of the Quaternary iv. soil sites, (particularly soil sub-groups and types) v. geomorphological sites vi. fossil fauna and assemblages 4. Revise and update County Geology Site (RIGS) descriptions. Review descriptions on SSSI citation sheets to identify any additional features of geodiversity interest that could be designated at regional (RIGS) level. 5. There are a number of issues relating to the collection and management of County Geology Sites (RIGS) data: i. lack of standardised information collected, ii. lack of up-to-date survey information for each site, iii. lack of adequate computerised information for each site, iv. lack of management plans/recommendations for each site. 6. Systems for the recording and wider reporting of temporary exposures of geological significance are not well developed. Formal watching briefs, such as those required for archaeological interests, could be established. 7. There is currently insufficient information pertaining to sites outside of the designated sites system i.e. sites in the wider landscape. 8. The audit has not established whether the museum and academic collections contain a comprehensive record of all the key mineral, rock and fossil specimens or species in Cornwall. 9. There is a need to audit and review the resources and skills available within existing partners, potential partners and other organisations or individuals. Geodiversity Action Plan, Cornwall and Isles of Scilly

10 Issues, opportunities and threats Major Geodiversity Issues in Cornwall and Isles of Scilly Issue Positive aspects Negative aspects Opportunities Threats Conservation designations protect reported sites. Planning and conservation policies Public awareness and appreciation Planning policies restrict development on sites and promote prudent development of mineral resources. General appreciation of Cornwall and Isles of Scilly s natural heritage is widespread. Strong, enthusiastic base of skills/activities to build on. Concept of geodiversity not fully integrated into policies. Perception that geodiversity is only valued if sites are designated. Sustained improvement to awareness requires long term plan and numerous activities. World Heritage Site status could offer further promotion and protection of geodiversity. Geodiversity input into Mineral Development Framework. Informal branding of publicity literature to reinforce a common message. Working practices and management plans overlook geodiversity. Public fails to engage with message that geodiversity is important. Minerals extraction and restoration Geodiversity value of Cornwall s resources is of national/international significance. Quarries provide valuable exposure sites. Loss of landscape features in areas of high sensitivity. Perception that all mining damages the environment. Conservation and educational potential can be recognised as part of restoration plans. Waste rock disposal impacts on land take. Poor management practices damage/neglect integrity sites. Agriculture and forestry Waste disposal and derelict land Good land management practices promote soil conservation and landscape geodiversity. Many abandoned mine sites are significant for geodiversity as well as biodiversity and industrial archaeology. Intensification of farming impacts on soil quality and structure. Visual impact of derelict sites increases pressure for redevelopment. Agri-environmental schemes to assist conservation Survey of old quarries may provide valuable geodiversity data and highlight sources of stone for building or hedging projects. Poor working practices lead to soil erosion. Large plantations reduce geological exposure. Unregulated waste disposal in abandoned quarries. Built development Use of local, distinctive building materials encouraged. Loss of exposures and landforms, impact on soils and landscape. Recording of geological features during temporary exposures. Any decline in environmental quality threatens economy. Tourism, amenity use and access Key promoters of Cornwall and Isles of Scilly s natural environment. Many landowners have positive attitude towards geodiversity. Concept of geodiversity not widely understood. Little direct involvement in geoconservation. Potential to develop geotourism. WHS bid raises awareness of mining landscape. Increased visits to geodiversity sites cause damage or exceed management capacity. Coastal erosion and climate change Cornwall and Isles of Scilly s geodiversity is valuable for research into sea-level and climatic changes. Increased rates of erosion in coastal areas. Changes to fluvial systems. May change range of geomorphology features and processes available for study. Flood and coastal defence plans in conflict with protection of geodiversity. Geodiversity Action Plan, Cornwall and Isles of Scilly

11 Major Geodiversity Issues in Cornwall and Isles of Scilly Issue Positive aspects Negative aspects Opportunities Threats Mineral and specimen collecting Public collections provide excellent educational resource to introduce geodiversity Excessive hammering and collection damages exposures. Private collections may provide untapped source of conservation potential. Lack of policy or code of practice to regulate collection. Biodiversity and Historic Environment Links Conservation bodies placing increased emphasis on linking geology to biodiversity. Protection of historic environment has a high profile in Cornwall and Isles of Scilly. Some landowners, businesses respond poorly to nature and heritage conservation approach. Develop geodiversity aspects to the watching brief archaeologists have for major and temporary excavations. Collaborative projects broaden potential funding sources. Geodiversity does not develop separate identity GAP could be linked with the Cornwall BAP process through the Biodiversity Initiative. Recommendations and action plans The Geodiversity Audit and qualitative assessment of the main issues, opportunities and threats facing geodiversity has allowed targets and recommendations to be developed for future geological conservation work in Cornwall and the Isles of Scilly. Action plans have been drawn up from each of the recommendations and targets identified. Action Plans delivering Recommendations 1 and 2 are the highest priority tasks and need to be addressed with immediate effect. Recommendations are summarised on the following page. Geodiversity Action Plan, Cornwall and Isles of Scilly

12 Recommendations Recommendation 1: Set-up infrastructure to deliver the GAP Whilst this GAP will provide the framework for taking forward work related to geodiversity conservation, a robust infrastructure needs to be established if the GAP is to be delivered, including the creation of a small steering group representing the key partners. Recommendation 2: Complete resources and skills audit Audit and review the resources and skills available from existing partners, potential partners and other organisations or individuals. This should also include identifying areas (both topicbased and geographical) for future research. Recommendation 3: Improve data coverage Improve and extend data collection, analysis and designation of County Geology Sites to close gaps in conservation coverage, complete the assessment of status for various geodiversity aspects and enhance the storage of data. Recommendation 4: Improve policy and working practices Further enable organisations to incorporate geodiversity conservation into policy and strategic documents, management plans and working practices. Recommendation 5: Raise public awareness The key priority for promoting geodiversity must be to raise awareness of the wider significance of rocks, soils and physical processes as a key part of our natural heritage, landscapes and scenery. This will require a more co-ordinated approach, using action plans to help guide development of a whole range of activities. Recommendation 6: Promote geotourism and amenity use Work with the tourism sector to promote geotourism and a greater understanding of the landscape. The quality of the natural (and built) environment is the main attraction which brings visitors to the region and geotourism could allow the shoulder months of the tourist season to be extended. Recommendation 7: Increase corporate awareness Develop links with companies and businesses, highlighting their impact on geodiversity conservation and increasing their awareness of key issues. Recommendation 8: Improve links with the biodiversity and historic environment sectors Highlight areas where links exist between biodiversity, geodiversity and the historic environment, as a means of promoting closer working relations and collaboration. Geodiversity Action Plan, Cornwall and Isles of Scilly

13 Chapter 1 Introduction 1.1 Overview Cornwall and the Isles of Scilly have a great diversity of rocks, soils, landscapes and mineral deposits, reflecting a rich and varied geological heritage that spans the last 500 million years of Earth s history. For some 130 million years, during the Devonian and Carboniferous periods, the geology in Cornwall evolved in a completely different manner to the rest of Britain. Deep marine conditions predominated in what is now Cornwall, while the rest of Britain sweltered under first desert and then shallow, tropical water conditions. The sediments and lavas deposited in marine basins were then uplifted and deformed by mountain-building events, forming slates and greenstones, and bringing a slice of the ocean crust onto land, now exposed on the Lizard. Molten granite subsequently intruded these rocks and as it cooled and crystallised, metal-rich fluids associated with the granites moved into fractures in the rocks and deposited ore minerals in veins and lodes. Many geological and geomorphological sites in Cornwall and the Isles of Scilly are of national and international importance and there is a growing recognition of the need to conserve and manage this highly distinctive geological heritage. Geodiversity finds itself in the same position as biodiversity 15 years ago, before the 1992 Earth Summit in Rio de Janeiro successfully threw sustainable development and biological diversity issues onto the radar screens of policy and decision makers and triggered the much wider public awareness of biodiversity that is found today. Within Cornwall and the Isles of Scilly there is a need to bring national and local targets for geological conservation together in a strategic plan that will provide a framework within which all geological resources and conservation projects can be assessed, prioritised, promoted and managed. The aim of this Geodiversity Action Plan (GAP) is to provide both a strategic framework for geodiversity in Cornwall and the Isles of Scilly and to identify projects and actions which take the development or conservation of geodiversity forward in a sustainable manner. The preparation of this Geodiversity Action Plan was initiated by Cornwall Wildlife Trust, through the Environmental Records Centre for Cornwall and the Isles of Scilly (ERCCIS), in collaboration with Cornwall RIGS Group. Cornwall RIGS Group is a voluntary organisation concerned with the conservation of important geology and geomorphology sites and raising awareness of Cornwall s unique geological heritage. Funding was obtained from English Nature, through DEFRA s Aggregates Levy Sustainability Fund Grant Scheme, for a project entitled Exploring the Geodiversity of Cornwall ; the principal element of which was the preparation of the first local GAP for Cornwall and the Isles of Scilly. Geodiversity Action Plan, Cornwall and Isles of Scilly

14 1.2 Geodiversity Action Plan Objectives 1. To audit the geodiversity of Cornwall and the Isles of Scilly, in order to identify and summarise the current status of our geological assets (Geodiversity Audit). 2. Use the Geodiversity Audit, together with a review of key issues affecting geodiversity, to inform the development of targets and action plans which provide for the future conservation and sustainable development of Cornwall and the Isles of Scilly s geology, geomorphology and landscape. The audit will seek to establish if the range and number of sites that have been identified are a representative reflection of the geodiversity in Cornwall and the Isles of Scilly, and highlight aspects of geodiversity that are not adequately represented or recognised in current conservation strategies. Many locations in Cornwall and the Isles of Scilly are now legally protected as Sites of Special Scientific Interest (SSSI) for their geological importance, or have been recognised under the Regionally Important Geological/geomorphological Sites (RIGS) conventions, and their conservation and continued protection is a responsibility we have to future generations. The audit will also draw attention to the significant natural resources found in the soils, rocks and minerals of Cornwall and the Isles of Scilly; resources which make an important contribution to the overall geodiversity of Cornwall and the Isles of Scilly. These features often achieve regional, national or indeed international importance in their own right; providing considerable geodiversity value and requiring careful management and stewardship. In many cases, such as temporary exposures in quarry faces or agricultural soils, designated conservation status would be impractical or inappropriate. Geodiversity encompasses features and processes which by their nature are dynamic and ephemeral. Important landforms and geomorphic processes, such as sand dunes and fluvial (river) features, often occur on a small scale and are dependent on finely balanced conditions, changes to which can substantially alter their viability. While the vulnerability of such features makes their recognition and site management more significant in the short-term, conservation strategies need to recognise that some change and ultimately loss is inevitable if surface processes are to be allowed to develop naturally. Conservation of some features may therefore be limited in timescale and responsive to the dynamics of systems. Development of action plans will enable delivery of local, site-based geological conservation of resources that are: Covered by legislation At risk or in decline Representative of the character or local distinctiveness of an area Rare Geodiversity Action Plan, Cornwall and Isles of Scilly

15 3. Improve recognition of the economic and amenity value of Cornwall and the Isles of Scilly s natural resources, in particular its geology and landscapes, and promote the sustainable development of these resources. Rocks and landscapes are the basis for much of Cornwall and the Isles of Scilly s beautiful scenery and provide the resources for a variety of recreational and leisure activities. The landscape around us is the result of present day processes but also those that operated in the past. Within our towns, villages and industrial sites, geological resources and landscapes have provided the building materials, architectural heritage and physical backdrop. Cornwall and the Isles of Scilly s geological features are therefore of immense cultural, amenity and economic value. The economic significance is particularly relevant to the tourism, agricultural and quarrying industries in Cornwall and the Isles of Scilly. Tourism is the largest single industry and the quality of the natural environment remains by far its most important attraction. The farming community plays a major role in the management, use and protection of our soils, rivers and landscapes; thereby also influencing habitats and ecosystems. Quarrying companies are major landowners and users of the geological resources in Cornwall and have a key role to play in geoconservation. Human activities are therefore significant forces controlling the shape, quantity and quality of our geological resources and we need to develop strategies for their sustainable use. 4. Promote awareness, at all levels from government policy makers through to school children and the wider public, of the following factors: The exceptional scientific and cultural value of Cornwall and the Isles of Scilly s geological heritage. The wider significance of rocks, soils and physical processes in our daily lives and as a key part of our natural heritage, landscapes and scenery. Cornwall and the Isles of Scilly s geological heritage is important in the historical development of geology and the broader earth sciences, particularly in relation to stratigraphy and economic geology. For example, the study of Cornish sites made a significant contribution to the original concept of the Devonian period of geological time. Our rocks, landscapes and mineral deposits retain their importance today as a scientific and cultural resource of national and international significance. Cornwall and the Isles of Scilly contain numerous sites with geological evidence of past changes to sea-level and climate, sites that can be studied to help understand contemporary climate change and develop appropriate mitigation strategies. Understanding environmental change on a variety of timescales, from comparison of climatic conditions and sea-levels to the long-term monitoring of impacts on ecosystems, requires knowledge of baseline conditions and trends. Geological systems provide some of this background data and it is therefore important to identify and protect those sites or landscapes which provide us with important information. Geodiversity Action Plan, Cornwall and Isles of Scilly

16 As well as specific sites, public (and private) collections of minerals, rocks and fossils have an important role to play in conserving Cornwall and the Isles of Scilly s geodiversity. Existing public collections have immense value as repositories of representative and/or rare samples of this geodiversity; and as a gateway for raising public awareness of our geological heritage. At planning and decision-making levels, in both industry and local government, the sustainable management of Cornwall and the Isles of Scilly s natural resources needs further integration into policies and practices. Environmental education has a role to play in highlighting how special Cornwall and the Isles of Scilly s geology is, and in providing a better understanding of its links to landscapes, habitats and biodiversity, industrial heritage, built environment and mineral extraction. 5. Encourage further involvement in geoconservation issues from local communities, industry, and the education sector. Interest in, and demand for, environmental and conservation based activities from community groups and individuals involved in lifelong learning has seen considerable growth in recent years. Highlighting the role of geodiversity within nature conservation will stimulate a greater appreciation of geoconservation within the community and lead to the inclusion of more geodiversity based activities within community projects and lifelong learning courses. While the minerals industry has to some extent taken the lead in promoting its geodiversity credentials, there are other sectors such tourism and the outdoor recreational industries, which rely just as heavily on the natural resources of Cornwall and the Isles of Scilly. Businesses in these sectors need to be encouraged to take a more active role in the conservation and promotion of the geodiversity that underpins their activities. The environmental and sustainable development strands of the National Curriculum provide a suitable framework within which to introduce the subjects of geodiversity and geoconservation. Materials and projects aimed at the school sector will foster an interest in conservation which can lead to more active participation in subsequent years. 6. Encourage wider collaboration between the earth science community and the biodiversity and historic environment communities. Soils, rocks and landscapes are an integral part of the natural history, cultural history and industrial archaeology of Cornwall and the Isles of Scilly. They provide the basis for the diversity of species and the active geomorphological processes that shape the moors, rivers and coasts to create varied habitats and ecosystems. Bedrock geology, soils and landforms have always had a critical influence on the places humans have chosen for all types of activities. Geology and geomorphology have a fundamental role in determining habitat type and hence an underpinning control on biodiversity. There is a relationship between rocks, soils, habitats and species; most terrestrial habitats cannot exist without the supporting medium of soils to sustain plant growth and soils cannot form without the geological processes acting on underlying rocks. Cornwall and the Isles of Scilly s biodiversity is inextricably linked to maintaining and managing the geological features Geodiversity Action Plan, Cornwall and Isles of Scilly

17 and geomorphological processes that provide the physical settings for habitats and species. Cornwall formed the comprehensive partnership known as the Cornwall Biodiversity Initiative (CBI) in 1996 and the Partnership s initial action was to produce a Biodiversity Action Plan (BAP) for Cornwall. This Plan entitled Cornwall s Biodiversity includes Audit and Priorities (Volume 1) and Action Plans (Volume 2). Volume 3 revises the earlier volumes to bring the BAP in line with more recent national guidelines. Implementation and monitoring of the Action Plans is ongoing under the auspices of the Cornwall Biodiversity Initiative. At present there is no BAP covering the Isles of Scilly. Conservation strategies for biodiversity in Cornwall and the Isles of Scilly are therefore at a much more advanced stage than for geodiversity and there is an opportunity to promote and fast-track progress on geological conservation with help and assistance from this very active and successful Biodiversity Initiative; linking the Geodiversity Action Plan with the Cornwall BAP process. Any exposures of rocks or sediments may also contain archaeological data and the sourcing of artefacts (ceramics, tone tools and building materials) is dependent on a good and accurate geological database. Mines, pits and quarries are of great interest to specialists from a range of disciplines, not least for their historic, industrial archaeological value. Quarries provided stone for dwellings, historic buildings and hedging, and remain significant as a source of materials for conservation and repair works. The interest and value of historic environment sites is wide ranging and includes: the landscape context of sites and their impact on local environments, evidence for changes in site use and technology through time, surviving industrial structures and the impact of industry on the cultural landscape of the surrounding area (smallholdings, field systems, housing, chapels, institutes etc.). In the near future there may be new opportunities to promote better working relationships between organisations and agencies involved in the historic environment, biodiversity and geodiversity. Parts of Cornwall s mining landscape have been nominated for World Heritage Site (WHS) status and the WHS Management Plan aims to promote such multidisciplinary links and their contribution to Cornwall s cultural distinctiveness. 1.3 Sources of Information and Consultation The Geodiversity Action Plan (GAP) has been prepared by reviewing existing geodiversity information and holding discussions with members of the Cornwall RIGS Group and a number of consultees Key Sources of Information A list of the key sources of information used in the production of this GAP is given in Appendix 1. In addition to these, the following data sources were also widely consulted: Geodiversity Action Plan, Cornwall and Isles of Scilly

18 Cornwall RIGS Group archives Proceedings of the Ussher Society District Council Local Plans Memoirs and Sheets of the British Geological Survey English Nature Research Reports, Natural Area Profiles, Shoreline Management Plans Websites and on-line databases from the following organisations were also important sources of information: UK RIGS ( Cornwall RIGS Group ( Cornwall County Council ( English Nature ( Consultation Process The organisations and individuals consulted whilst producing the GAP are given in Appendix 2; they all had the opportunity to comment on an external consultation draft of the GAP and over a third responded with comments. Cornwall RIGS Group Executive Committee members discussed the contents of the GAP at a number of their committee meetings and also had the opportunity to comment on an earlier internal draft. 1.4 Summary The aim and objectives of the Geodiversity Action Plan are summarised in the box on the following page. Geodiversity Action Plan, Cornwall and Isles of Scilly

19 Geodiversity Action Plan: Aim and Objectives GAP aim: To provide both a strategic framework for geodiversity in Cornwall and the Isles of Scilly and to identify projects and actions which take the development or conservation of geodiversity forward in a sustainable manner. GAP objectives: 1. Undertake an audit of the geodiversity of Cornwall and the Isles of Scilly (Geodiversity Audit), in order to identify and summarise the current status of our geological assets (covering the range of geological, geomorphological and soil and landscape features present and also the physical and human resources available). 2. Develop targets and action plans which provide for the future geoconservation and sustainable development of Cornwall and the Isles of Scilly s geodiversity and ensure the conservation of at least adequate representative examples of the geodiversity identified in the Audit. 3. Improve recognition of the economic and amenity value of Cornwall and the Isles of Scilly s natural resources, in particular its geology and landscapes, and promote the sustainable development of these resources. 4. Promote awareness, at all levels from government policy makers through to school children and the wider public, of the following factors: a. The exceptional scientific and cultural value of Cornwall and the Isles of Scilly s geological heritage. b. The wider significance of rocks, soils and physical processes as a key part of our natural heritage, landscapes and scenery. 5. Encourage greater involvement in geoconservation issues from local communities and businesses. 6. Encourage wider collaboration between the earth science community and the biodiversity and historic environment communities. Geodiversity Action Plan, Cornwall and Isles of Scilly

20 left blank intentionally Geodiversity Action Plan, Cornwall and Isles of Scilly

21 Chapter 2 Geodiversity Audit 2.1 Scope of Audit The purpose of this Audit is to identify, summarise and classify the principal geological, geomorphological, soil and landscape features and natural resources that together make up Cornwall and the Isles of Scilly s geodiversity. By reviewing the number, location and features of exposure and integrity sites currently identified and designated as conservation sites within Cornwall and the Isles of Scilly, an assessment can be made of the current status of the protection being afforded to these principal features. Sites of Special Scientific Interest (SSSI) and Regionally Important Geological/geomorphological Sites (RIGS) are the most frequent designations used to protect geological features. The Audit has, however, reviewed all aspects of geodiversity and not just those under current conservation designations. Many features of Cornwall and the Isles of Scilly s geodiversity achieve regional, national or indeed international status in their own right without falling within the RIGS or SSSI systems of designation. For example, many of the current or historic mineral extraction areas provide extensive additional exposure sites of considerable geodiversity and economic value. Sustainable development and/or sympathetic management of these features is required, which relies on the owner or operator being aware of the geodiversity value of the site (or specimens in the case of collections). International schemes for nominating and designating areas or sites of outstanding geodiversity include European Geoparks, which are endorsed as part of UNESCO s Global Geopark Network, and the Geosites scheme. Similarly there are a number of organisations such as the European Association for the Protection of the Geological Heritage which exist to promote dialogue on geological conservation and good practice among member countries. Consideration of these broader international frameworks is, however, beyond the scope of this 1 st edition of the GAP Approach It should be acknowledged that the sort of comprehensive audit achieved by the Cornwall Biodiversity Initiative (CBI) in Cornwall s Biodiversity Action Plan (BAP) is beyond the scope and resources of the current Exploring the Geodiversity of Cornwall Project. A synthesis of the conservation status of every individual rock type, mineral, fossil, stratigraphic unit etc. within Cornwall and the Isles of Scilly has not been attempted to the same depth achieved in the BAP, which addressed all taxonomic groups and individual species of conservation concern within them. It is hoped, however, that in itself this Audit provides an initial framework within which further detail can be added and refinements made on an ongoing basis. The detailed findings of the Geodiversity Audit present a very technical account of all aspects of Cornwall and the Isles of Scilly s geology and geomorphology, at a level which is inappropriate for inclusion in the main text of the Geodiversity Action Plan (GAP). The geological overview and the key findings from each section are therefore presented here; ultimately the detailed technical report on the Audit will be made Geodiversity Action Plan, Cornwall and Isles of Scilly

22 available through the websites of the Environmental Records Centre for Cornwall and the Isles of Scilly (ERCCIS) and the Cornwall RIGS Group. Section 2.2 provides a brief history of the tectonic and geological evolution of Cornwall and the Isles of Scilly and sections 2.3 to 2.8 then group the Audit s key findings into sensible geological blocks. These sections should be read in conjunction with the conservation sites list in Table 1 and the brief descriptions of each site contained in Appendices 3 and 4. Section 2.9 includes a very limited review of the organisations with geological/geomorphological skills and resources, as well as assessing the status of the collection and storage of data within the current conservation framework in Cornwall and the Isles of Scilly. In addition to reviewing specific exposure and integrity sites in Cornwall and the Isles of Scilly, consideration has also been given to the public (and private) collections of minerals, rocks and fossils which have an important role to play in conserving Cornwall and the Isles of Scilly s geodiversity. Existing public collections have immense value as repositories of representative and/or rare samples of this geodiversity; and as a gateway for raising public awareness of our geological heritage. Key data sources used in the compilation of this Audit are given in Appendix 1 and there is also a full list of References Geological SSSIs and GCR sites The Nature Conservancy Council (NCC) began a review of earth science conservation in the late 1970s which subsequently led to the Geological Conservation Review (GCR), a national programme to identify earth science sites of national scientific importance for their geology or geomorphology. The NCC subsequently split into separate statutory agencies by country; English Nature is the statutory body with responsibility for England; with the Joint Nature Conservancy Council (JNCC) retaining responsibility for the management and publication of GCR information. The GCR site series recognised sites on the basis of three, overlapping criteria: sites of international importance, sites that are nationally important because they show exceptional (rare or classic ) features and sites that are nationally important because they are representative of a key earth science feature, event or process in Britain. Although minor amendments continue to be made to the GCR, the majority of GCR sites were identified by 1990 and have now been designated as geological, or combined biological and geological, Sites of Special Scientific Interest (SSSI) by the statutory nature conservation agencies (i.e. English Nature for sites in England, including Cornwall and the Isles of Scilly). The term Site of Special Scientific Interest (SSSI) applies to areas of land that have been notified under the provisions of the Wildlife and Countryside Act 1981, as being of special interest by reason of any of its flora, fauna, geological or physiographical features. The SSSI system is the main nature conservation designation in Great Geodiversity Action Plan, Cornwall and Isles of Scilly

23 Britain, designating sites of national importance. SSSI sites are either biological SSSIs, geological SSSIs or a combination of both. Designation as a SSSI provides a mechanism which ensures that English Nature must, legally, be consulted about any development or activity that would damage the scientific interest for which the site is notified. A potentially damaging operation can only be carried out on a SSSI if English Nature has given its consent or if the operation is undertaken in accordance with a management agreement. For some geological SSSIs in England, a Site Management Brief is also available. Table 1 provides a list of the SSSI sites (geological and geological/biological) in Cornwall and the Isles of Scilly which contain geodiversity features of national importance, sub-divided into various aspects of geology/geomorphology. Sites may be important exposure or integrity sites for more than one aspect and therefore appear in several sections. Brief descriptions of each of these SSSIs are given in Appendix 3. Table 1: Conservation sites list for selected aspects of Cornwall and the Isles of Scilly s geodiversity (as at 31/12/04). Geodiversity Audit heading Pre-Devonian Basement Looe Basin Gramscatho Basin Trevone-South Devon Basin SSSI sites (statutory) Aire Point to Carrick Du* Caerthillian to Kennack Cuckoo Rock to Turbot Point *exposures of basement material occur but are not specifically cited Kingsand to Sandway Point Rame Head and Whitsand Bay Polyne Quarry Aire Point to Carrick Du Baulk Head to Mullion Cuckoo Rock to Turbot Point Cudden Point to Prussia Cove Gerrans Bay to Camels Cove Godrevy Head to St Agnes Meneage Coastal Section Mullion Cliff to Predannack Cliff Penhale Dunes Penlee Point Penlee Quarry Porthleven Cliffs East Rosemullion Tater-Du Bedruthan Steps and Park Head Clicker Tor Quarry Harbour Cove Pentire Peninsula Rock Dunes County Geology Sites (RIGS, non-statutory) Carne Quarries Black Head-Ropehaven Carlyon Bay East Carlyon Bay West Cawsand Bay Duporth Gamas Point Lantic Bay Sandheap Point Seaton Beach St Germans Quay Whipsiderry Black Cliff Caragloose Point Carne Quarries Fishing Cove Great and Little Hogus Jacka Point Porthcadjack Cove Tubb's Mill Quarry Cant Hill Lowhill Quarry & Forder Quarries Port Arthur Port Quin Stepper Point Geodiversity Action Plan, Cornwall and Isles of Scilly

24 Geodiversity Audit heading Tavy Basin Culm Basin (north of Rusey Fault Zone) Variscan Structures (key sites) Lizard Complex Granites and associated rocks (elvans, contact metamorphism) Other associated rocks (rhyolite, lamprophyres) SSSI sites (statutory) Rosenun Lane Stepper Point Trebetherick Point Trevone Bay Trevose Head and Constantine Bay Crocadon Quarry Greystone Quarry Polyphant Stourscombe Quarry Tintagel Cliffs Viverdon Quarry Yeolmbridge Quarry Boscastle to Widemouth Bude Coast Duckpool to Furzey Cove Boscastle to Widemouth Bude Coast Cuckoo Rock to Turbot Point Godrevy Head to St Agnes Greystone Quarry Penhale Dunes Pentire Peninsula Porthleven Cliffs East Rosemullion Stepper Point Tintagel Cliffs Trevone Bay Trevose Head and Constantine Bay Baulk Head to Mullion Caerthillian to Kennack Coverack Cove & Dolor Point Coverack to Porthoustock Kennack to Coverack Meneage Coastal Section Mullion Cliff to Predannick Cliff West Lizard Aire Point to Carrick Du Belowda Beacon Carn Grey Rock & Quarry Cameron Quarry Cligga Head De Lank Quarries Folly Rocks Luxulyan Quarry Penlee Point Porthcew Porthgwarra to Pordenack Point Roche Rock St Mewan Beacon St Michael s Mount Tregargus Quarries Trelavour Downs Tremearne Par Wheal Martyn Kingsand to Sandway Point Aire Point to Carrick Du Cameron Quarry County Geology Sites (RIGS, non-statutory) Wearde Area Wearde Quay Lanterdan Oldwit Lane Penfoot Quarry South Petherwin Underwood Upton Coast Carlyon Bay East Carne Quarries Fishing Cove Lantic Bay Porthcadjack Cove Portnadler Bay Trebrown Upton Coast Countybridge Quarry Downas Cove to Pedn Boar Enys Head Beacon Hill Carn Brea Flat Marsh Cutting Goonbarrow Helman Tor Newgate Cutting Shallow Water Hill Cutting The Cheesewring Tremore Quarry East Tremore Quarry West Tresayes Venton Cove Wheal Hazard Wheal Remfry Wicca Pool The Gannel Quarry Withnoe Countybridge Quarry Croft Gothal Geodiversity Action Plan, Cornwall and Isles of Scilly

25 Geodiversity Audit heading Mineralisation and alteration Tertiary Quaternary sediments Geomorphology SSSI sites (statutory) Cligga Head Godrevy Head to St Agnes Great Wheal Fortune Hingston Down Quarry & Consols Lidcott Mine Mulberry Downs Quarry Penberthy Croft Mine Penhale Dunes Penlee Quarry Porthgwarra to Pordenack St Michael s Mount South Terras Mine Tremearne Par Trevaunance Cove Wheal Alfred Wheal Gorland Wheal Penrose St Agnes Beacon Pits St Erth Sand Pits Aire Point to Carrick Du Boscawen Castle Down (Tresco), Isles of Scilly Chapel Down (St Martin s), Isles of Scilly Dozmary Pool Gerrans Bay to Camel Cove Godrevy Head to St Agnes Gugh, Isles of Scilly Hawkstor Pit Higher Moors & Porth Hellick Pool (St Mary s), Isles of Scilly Porth Seal (St Martin s), Isles of Scilly Porthleven Cliffs Porthloo, Isles of Scilly Tean, Isles of Scilly. Trebetherick Point Watermill Cove, Isles of Scilly. White Island (off St Martin s), Isles of Scilly Boscawen Eastern Isles, Isles of Scilly Gwithian to Mexico Towans Higher Moors & Porth Hellick Pool (St Mary s), Isles of Scilly Loe Pool Peninnis Head (St Mary s), Isles of Scilly Rame Head and Whitsand Bay Tintagel Cliffs County Geology Sites (RIGS, non-statutory) Geevor Mine Ore Stockpile Gilson's Cove Mine Great Wheal Fortune Gryll's Bunny Harrowbarrow Mine Hobb's Hill Kerriack Cove Kit Hill Lambriggan Mine New Mexico Shaft, Geevor Redmoor Mine Stowe's Section, Wheal Phoenix Trewavas Mine Tye Rocks Wheal Basset Wheal Carpenter Wheal Cock Wheal Drea Wheal Edward Wheal Hazard Wheal Jane East Wheal Johnny Wheal Rose Wheal Uny Crousa Common Luxulyan Valley Carlyon Bay East Carlyon Bay West Countybridge Quarry Crowstone Cliff Fistral Bay Praa Sands The Hutches Upton Coast Bog Inn Duckpool Valley Fowey Estuary Helman Tor Lowland Point to Trevalsoe Luxulyan Valley Maindale The Cheesewring Trebarwith Stream West Lizard Cliffs Geodiversity Action Plan, Cornwall and Isles of Scilly

26 2.1.3 County Geology Sites (RIGS) The Nature Conservancy Council s strategy for earth science conservation also formalised the concept of Regionally Important Geological/Geomorphological Sites (RIGS); sites within a county that are considered worthy of protection for their Earth Science importance but are not as protected as SSSIs. RIGS are currently considered the most important places for recognising and thereby protecting important earth science and landscape features outside statutorily protected areas. The term has been widely adopted to describe locally and regionally important earth science sites. RIGS are not statutorily designated. If sites are notified to the local planning authority they can be registered as conservation sites and listed in local authorities development plans, thereby affording a degree of protection through the planning process. This is the system currently operated in Cornwall and the Isles of Scilly. RIGS are broadly equivalent to County Wildlife Sites and other non-statutory wildlife designations in their level of protection through the planning system. As such, RIGS sites are also commonly referred to as County Geology Sites within Cornwall; and this terminology is adopted throughout this Plan. Although the selection criteria for designating County Geology Sites (or RIGS) are developed locally they follow national guidelines from organisations such as UKRIGS and English Nature. The criteria for selection are based on a site s value in one (or more) of four key areas: Educational fieldwork in primary and secondary schools, at undergraduate level and in adult education courses Study by both professional and amateur earth scientists. Such sites demonstrate, alone or as part of a network, the geology or geomorphology of an area Historical significance in terms of important advances in earth science knowledge Aesthetic qualities in the landscape, particularly in relation to promoting public awareness and appreciation of earth sciences The County Geology Sites (RIGS) system is usually operated at county or unitary authority level, or where regions or metropolitan councils have distinct identities. The various RIGS groups define their own selection criteria and then aim to select representative sites and a variety of other sites (exposure and integrity) which reflect the geodiversity of a region. County Geology Sites (RIGS) may also be identified as areas important for their educational value, research potential and for the wider appreciation of Earth heritage. The Cornwall RIGS Group represents Cornwall and the Isles of Scilly. Table 1 provides a list of the County Geology Sites (RIGS) designated in Cornwall and the Isles of Scilly, sub-divided into various aspects of geology/geomorphology. Brief descriptions of each of these sites are given in Appendix 4. Geodiversity Action Plan, Cornwall and Isles of Scilly

27 2.1.4 Other Nature Conservation Sites A network of statutory and non-statutory sites, identified or designated for their conservation value, also offer varying degrees of protection for any features of geodiversity interest; although these sites often imply protection rather than providing explicitly for geoconservation in their citations. Landscape features in Cornwall and the Isles of Scilly have, in particular, a raft of conservation designations. Conservation sites that may potentially contain geodiversity interest include: Areas of Outstanding Natural Beauty (AONB), which include Heritage Coasts; National Nature Reserves (NNR); Special Areas of Conservation and Special Protection Areas (SAC/SPA); biological SSSIs and Areas of Great Landscape Value (AGLV). The coverage in Cornwall and the Isles of Scilly of many of the different site designations and nature reserves is shown in Table 2, although it should be noted that many of these designations overlap. Figures 1A and 1B, on the following pages, illustrate the location and extent of these designated sites and reserves. Table 2: Type and coverage of designated sites and nature reserves in Cornwall and the Isles of Scilly. Designation Number Area (ha) Designated Sites (Statutory): International: SPA* 3 sites 3,391 ha SAC* 17 sites 45,668 ha Ramsar 1 site 401 ha National: National Nature Reserve 3 reserves 2,053 ha SSSI (total - all sites) 166 sites 21,070 ha of which SSSI (geological) 53 sites 914 ha SSSI (geological and biological) 34 sites 5235 ha AONB 14 sites 105,608 ha Local Nature Reserve 11 sites 426 ha Conservation Areas 138 areas 3,912 ha Designated Sites (Non-statutory) County Wildlife Sites 627 sites 55,106 ha County Geology Sites (RIGS) 91 sites 1,621 ha AGLV 26 sites 87,585 ha Nature Reserves/Ownership The National Trust ownership 49 property units 9,924 ha CWT Reserves 54 reserves 1,919 ha Woodland Trust Reserves 25 reserves 264 ha RSPB Reserves 2 reserves 181 ha * Tamar SPA/SAC area has been adjusted to exclude the part of it that is in Devon. Former AGSV and AGHV designations have been replaced by AGLV and other key site and area designations. Planning implications of the various designations are discussed in Chapter 4. Geodiversity Action Plan, Cornwall and Isles of Scilly

28 Figure 1A: Location of geological or geomorphological related designated sites in Cornwall and the Isles of Scilly. Geodiversity Action Plan, Cornwall and Isles of Scilly

29 Figure 1B: Location of other (non-geological) nature or landscape conservation sites in Cornwall and the Isles of Scilly. Geodiversity Action Plan, Cornwall and Isles of Scilly

30 Figure 1A maps out the locations of all the geologically related designated sites in Cornwall and the Isles of Scilly; both statutory (SSSIs) and non-statutory (County Geology Sites); together with the locations of the two Geological Nature Reserves in Cornwall (refer to section 4.4). Figure 1B maps out the locations of all non-geology related nature conservation sites in Cornwall and the Isles of Scilly (statutory and non-statutory) together with other nature reserves. Also shown on this map are the boundaries of the Cornwall AONB and the Isles of Scilly AONB and Areas of Great Landscape Value (AGLV). These designations afford protection to the overall character of the landscape rather than to any individual geodiversity features. The extensive coverage of land designated for some form of nature or landscape conservation (Figure 1B) emphasises the high quality and value afforded to the natural environment in both Cornwall and the Isles of Scilly. In comparison, however, the coverage of geology-related conservation sites is substantially smaller in its extent (Figure 1A). Whilst non-geology site designations imply safe ownership in terms of, for example, gross changes through built development, they do not imply that there will be appropriate management to conserve or protect any geodiversity interest(s) that may be present. Where these designations refer to protection of the general character of an area rather than individual features, the attitudes and policies of landowners and local planning authorities become particularly important. There is a need to increase geology-related site designations and/or to ensure policies for nature conservation sites and reserves take account of the geodiversity interest. Geodiversity Action Plan, Cornwall and Isles of Scilly

31 2.2 Geological History Cornwall and the Isles of Scilly s geology is related to plate tectonic movements over the last 500 million years, which have changed the geographical position of Cornwall from some 60 o south of the equator to its present location in the northern hemisphere (50 o N). From around 400 million years ago, for a period of some 130 million years, the geology in Cornwall, located on the margins of an ocean, evolved in a completely different manner to the rest of Britain. Many of the distinctive rocks of Cornwall and the Isles of Scilly were formed in a zone where the movement of tectonic plates progressively opened and then closed sedimentary basins, as the Earth s crust was firstly pulled apart (rifted) to form a new ocean and then pushed back again. While open, these sedimentary basins were the site of large scale deposition of sediments and volcanic material; their closure piled up these pre-existing rocks, compressing and deforming them as part of a mountainbuilding event. The oldest and most extensive sedimentary rocks in Cornwall were deposited in five major east-west trending basins, defined by major fault boundaries. The most southerly basin, known as the Gramscatho Basin, was on the margin of a major oceanic region. Remnants of the ocean floor were later thrust up and onto the sedimentary rocks of this basin to form the Lizard Complex. Four other basins; known from south to north as the Looe Basin, Trevone-South Devon Basin, Tavy Basin and Culm Basin; developed in a series of northwards extensions. Figure 2 is a simplified geological map of Cornwall which illustrates the relative position of these sedimentary basins. The rifting of the crust also allowed the generation of volcanic magmas, which erupted or were emplaced at shallow depths, within the sedimentary sequences. Variations in the locations and types of sediment supplied to each of the major basins, and differences in their environment of deposition, account for the variations seen in these sedimentary rocks in Cornwall. As the tectonic regime changed to one of compression (closure of the ocean), collision-related deformation progressed northward as part of a relatively slow and continuous sequence. In each basin in turn, the sediments were piled up, thrust over each other and deformed (folded and faulted) until movement on major faults was no longer possible and the pressure could be transmitted to the next basin. This was known as the Variscan orogeny. Sedimentation therefore continued in basins to the north while basins to the south were being deformed. During these deformation events, the large scale action of both heat and pressure caused the rocks in these former basins to change to their metamorphic equivalents (a process known as regional metamorphism), creating new minerals within them and generating new textures. Regional metamorphism in Cornwall and the Isles of Scilly was under conditions of relatively moderate temperature, low pressure and high stress; giving rise to a relatively low grade of metamorphism and leaving many rocks seemingly unchanged when observed in the field. More obvious signs of the deformation events come from structures such as faults and folds which dislocate and disrupt the rock mass. One distinctive characteristic of Cornwall s metamorphic legacy is, however, the widespread presence of slates formed from the original mudstone rocks. Geodiversity Action Plan, Cornwall and Isles of Scilly

32 Subsequent relaxation of these tectonic forces released pressures deep in the Earth s crust and triggered melting of rocks and the generation of granite magmas. These magmas were then emplaced at higher levels in the crust to form the Cornubian batholith. Subsequent erosion of the overlying rocks has exposed a series of granite plutons; the locations of the major plutons in Cornwall are shown on Figure 2. Granite also forms the bedrock to the Isles of Scilly. Prominent fracture systems were developed and/or reactivated in both the granite and the surrounding country rocks and provided structural pathways for the migration of hydrothermal fluids. These fluids contained tin (Sn), copper (Cu) and other metal species which were deposited in the fractures and wall-rocks to form mineral bearing lodes. This mineralisation formed around 270 million years ago and for most of the rest of its geological history, Cornwall and the Isles of Scilly formed a major land mass that was subjected to uplift, deep weathering and erosion under desert to sub-tropical conditions as the continent drifted northwards. Deep chemical weathering of some upper parts of the granite batholith further altered many of the feldspar minerals in the granite, creating extensive areas of china clay alteration (kaolinisation). Conditions onshore eventually became more temperate and minor marine incursions led to localised deposition of some shallow-water sediments. Weathering and erosion continued to dominate, however, and almost all the rocks formed in the last 270 million years have been lost from Cornwall and the Isles of Scilly s geological record (at least onshore). The last two million years (called the Quaternary) has seen major climate fluctuations and associated changes in sea-levels. These changes have had a marked effect on the sub-surface deposits and landforms in Cornwall and the Isles of Scilly but the Quaternary sequences found are very fragmentary. At least one of the major cold periods produced ice sheets close enough to the mainland to produce periglacial (tundra-like) conditions in Cornwall and may have brought glacial activity to the Isles of Scilly. The major sea-level rise after the last glacial period had a profound effect on the geomorphology and landscape seen today; controlling development of Cornwall s rias (flooded valleys), the Isles of Scilly archipelago, associated coastal geomorphological features (sand dunes, marshes) and the current rates of erosion and sedimentation. Footnote Strictly speaking, the majority of Devonian rocks we see in Cornwall today are meta-sediments i.e. sedimentary rocks that have been metamorphosed, or meta-basites, metamorphosed basic igneous rocks. The metamorphism experienced, however, is generally of low grade and many rock types retain their internal structures. These rocks are commonly referred to in the literature and in this report by their sedimentary and igneous names, (sandstones, conglomerates, dolerites etc.). The exception is where mudstones have been altered and new minerals grown in alignment to give a well-defined, slaty cleavage. In this report these rocks are referred to as slates. To add further to the confusion there are a plethora of local terms for some rock types and these are explained where first encountered in the text. The terminology Ma is used to indicate the age of rocks in millions of years before present i.e. most of our Devonian age sediments are million years old, shown here as Ma. Definitions for many of the geological terms can be found in the Glossary. Geodiversity Action Plan, Cornwall and Isles of Scilly

33 Geodiversity Action Plan, Cornwall and Isles of Scilly